I tried to update my project to Swift 3, my project has support for ios8 as well.
While trying to update the cocoapods, I am getting issue that AlamofireObjectMapper
EDIT Alamofire 4.1.0
Support for iOS 8.0 and macOS 10.10 is back!
You cannot update to Swift 3 without dropping support for iOS 8, I'm afraid. The reason is that the Swift 3 version of Alamofire is 4.0 and the developers have decided to drop support for iOS 8.0. The reasons can be found here : https://github.com/Alamofire/Alamofire/issues/1367#issuecomment-235803404
Therefore you can continue supporting iOS 8 by using the latest Swift 2.3 release of Alamofire (3.5.1) and AlamofireObjectMapper or drop support for iOS 8.